Iranian police had requested the extradition of Man Haron Monis, the gunman who was shot dead in the Martin Place siege, 14 years ago but Australian authorities would not hand him over, Iran's police chief has claimed in comments to reporters.

Monis had committed a number of "violent" and fraud-related offences before he fled the country "in disguise" in 1996, according to Iran's chief of police, General Ismail Ahmadi Moghaddam.

At the time, Monis went by the name of Mohammad Hassan Manteqi. He fled first to Malaysia in 1996 and then to Australia, General Moghaddam claimed.

Monis applied for, and was in 2001 granted, refugee status in Australia.

General Moghaddam told the Iranian Mehr News Agency that Monis posed as a cleric at the time to gain political asylum. Earlier Monis had been the manager of a travel agency in Iran, authorities there said.

Advertisement

General Moghaddam said Iranian police spent four years collecting evidence against Monis, before seeking his extradition to Iran from Australia.

But that request was knocked back, General Moghaddam claimed.

"It lasted four years to collect evidence on Manteqi's [Monis'] identification documents and we reported this to the Australian police but since Australia has no extradition treaty with Iran, they didn't extradite him," General Moghaddam told the Mehr News Agency.

Once the Australian government granted asylum to Monis, it would have been in breach of the Refugee Convention to send him back to Iran, unless it was proved that he had obtained that status through fraud.

The government would also have been highly unlikely to send him back while his asylum application was pending, though it might have had to consider evidence provided by Iran of alleged crimes carried out by Monis in his native country.

Monis, 50, was shot dead when police stormed into the Lindt Chocolat Cafe just after 2am on Tuesday, more than 16 hours after he entered the cafe armed with a gun and held 17 customers and staff hostage.

The NSW government has called for an investigation into why Monis "slipped through the cracks" of the judicial system and was released from custody.

General Moghaddam said Iranian authorities were prepared to work with Australian police to investigate his past.

"Our position is clear in this regard; all countries should co-operate to avoid such issues if there is international organised crime today," General Moghaddam said.

The Department of Foreign Affairs and Trade is being contacted for comment.

After years of diplomatic isolation from the West, Shiite-dominated Iran and the Western world have found areas of agreement such as battling so-called Islamic State militants. Ongoing discussions about limits on Iran's nuclear program have made Iran more sensitive about its image on the world stage.